Ferries are used to transport vehicles and passengers across bodies of water throughout the world. A common general configuration for a passenger/vehicle ferry is the so called “Roll On/Roll Off” design (also identified by the acronyms “RORO” and “ro-ro”). RORO vessels have built-in side, bow and/or stern ports which allow the vehicles to be efficiently “rolled on” and “rolled off” the vessel when in port. (This is in contrast to the more traditional lo-lo (lift on-lift off) vessels which use a crane to load and unload cargo.)
Some RORO type vehicle/passenger ferries have one or more vehicle decks running the length of the vessel, each deck comprising a plurality of vehicle parking lanes, and vehicle access means at the bow and stern (or at either “end” of the vessel in the case of vessels configured to proceed and maneuver equally well in either direction, and thus lacking dedicated bows and sterns). Typically, with such bow/stern-loading ferry, vehicles are loaded by having each vehicle operator drive his or her vehicle on to the ferry and park it in location as designated by ferry staff. Similarly, each vehicle is unloaded by having each vehicle operator drive it off the ferry. This vehicle-operator loading and unloading permits the ferries to be rapidly loaded and unloaded. One slight wrinkle with bow/stern-loading ferries is that as the berthing facilities for such ferries typically only provide vehicle access to one end of the ferry, unless such a ferry is turned after a first set of vehicles is unloaded, the set of vehicles next loaded will be facing in the opposite direction within the ferry as compared to the first set. This means that ferries having dedicated bows and sterns, that is, a preferred direction of travel through the water, must frequently be turned at the end of a passage and brought into the loading/unloading facility stern-first to enable vehicle operators to drive their vehicles forward when exiting the ferry. With a conventional vessel configuration in which the bridge, and thus the helm and other vessel controls, is located closer to the bow than to the stern, stern-first maneuvering is typically more difficult than bow-first maneuvering, in part because of reduced visibility aft compared to visibility forward.
In some cases, such bow/stern-loading ferries are essentially barge-like, having a single uncovered vehicle deck. In other cases, particularly with larger ferries having more than one vehicle deck (i.e. having a vehicle deck above another vehicle deck), the vehicle decks are enclosed within the vessel. These large ferries typically have large ports at the bow and stern, with associated doors that are opened to permit vehicles to enter and exit the vehicle decks, and are closed when the vessel is underway to prevent spray or, in the case of stormy conditions, larger volumes of water from entering the vehicle decks. Some ferries having more than one vehicle deck have only a single pair of vehicle ports; i.e. they provide direct external access to only one vehicle deck and have internal ramps or lifts to permit vehicles to be moved between vehicle decks. However, it is more common for ferries having more than one vehicle deck to also have a second pair of vehicle access ports, with a lower pair of access ports permitting vehicles to directly enter and exit a lower vehicle deck, and an upper pair of access ports permitting vehicles to directly enter and exit an upper vehicle deck.
Ferries making regular runs typically have associated dedicated berthing facilities. Such dedicated berthing facilities for use with bow/stern loading ferries having two pairs of access ports,(i.e. a pair of upper access ports and a pair of lower access ports), typically include two independently operable loading/unloading bridges, one for each pair of access ports. Typically, each such loading/unloading bridge is pivotally attached to a shore facility at its proximal end and is raised and lowered by conventional means for raising and lowering such pivoting bridges (typically, a pair of hydraulic rams, one on each side of the bridge). Typically, the distal portion of each bridge is not directly supported and is essentially a cantilever. In use, once a ferry is secure in the desired loading/unloading position, the distal end of each bridge is lowered to the deck of the relevant access port to provide a vehicle path for loading and unloading. Typically each such bridge has a transition apron pivotally attached to the distal end of the bridge, such that when the distal end of the bridge is brought into proximity with the deck of the access port, the distal end of the transition apron settles onto the deck to provide a transitional vehicle pathway between the vehicle deck and the bridge deck. Typically, due primarily to visibility limitations, it is necessary to have two operators for such double bridge arrangements, one operator for each bridge.
Dolphins are often important components of dedicated berthing facilities for ferries. The term “dolphin” is conventionally used to mean a structure against which a vessel may lay while moored or during a mooring operation. Typically, a dolphin for use with large vessels comprises several piles driven into the seabed in relatively close proximity and attached one to the other so as to provide mutual support to withstand vessel impact forces. A “turning dolphin” is a dolphin used to assist in turning a vessel by laying the vessel against the turning dolphin and causing the vessel to pivot about the turning dolphin. Dolphins used in dedicated ferry berthing facilities often have large rubber bumpers intended to assist in absorbing vessel impact forces. However, such rubber bumpers tend to cause vessels striking them to rebound in an undesirable manner.
To keep costs down and reduce delays, it is preferable for ferry dockings to be accomplished without the assistance of a support vessel such as a tug-boat. Conventionally, dedicated berthing facilities for bow/stern-loading ferries include two rows of dolphins, one on each side of the preferred path to the docking position, the two rows of dolphins being closer together at their near-shore ends than at their outer ends. In this way, if a ferry approaching the docking position diverges from the preferred path it will contact a dolphin so as to be prevented from further divergence from the preferred path. If a ferry hits a conventional dolphin with sufficient force, the ferry will rebound away from the dolphin. This is why there are typically two rows of dolphins; in cases of a significant rebound, the ferry will impact the other row of dolphins, which will limit the ferries divergence from the preferred path. However, if a ferry rebounds with sufficient speed, it could be dangerous for passengers, particularly if they are on foot within the ferry. As the two rows of dolphins typically converge towards their near-shore ends, the amount of divergence from the preferred path permitted by the dolphins diminishes as the ferry approaches the docking position.
Typically, a ferry berthing facility is preferably located so as to make the ferry passage as short as possible while still providing reasonable road access to the facility, and thus ferry berthing facilities may be relatively unprotected with respect to the wind and wave effects of storm conditions, and may be exposed to strong and changing currents. As well, as with many berthing facilities, dedicated berthing facilities for ferries must be able to accommodate changes in water level, typically relatively frequent and rapid changes in the case of facilities in locations subject to tides, and less frequent changes, perhaps seasonal, in the case of facilities on lakes or other non-tidal bodies of water.
Berthing structures of various designs are used as a means of transport of vehicles and passengers between a ferry or ship, and the shore, as well as for moorage for the ferry or ship. Rigid pilings are often used to support and anchor the berthing structure to the seabed thus providing a rigid berthing structure for convenient and reliable access from the shore to the ferry. A disadvantage of a rigid berthing structure is that it must be massive in order to absorb the berthing impact energy of a ship. The pilings used to anchor such berthing structures are susceptible to breakage if exposed to excessive transverse load from a berthing ship, said transverse load being applied to the piling remotely from the point of attachment of the piling to the seabed. Down time and cost for repair of the pilings may be significant. Damage to a fixed, rigid berthing structure may also result from severe weather conditions. A floating berth has the advantage that it will dynamically adjust to tidal conditions, however, such floating berths lack the rigidity of a fixed berth. Further, floating berths may still be susceptible to damage from berthing impact forces.
Accordingly, a berthing structure is required that is strong and capable of absorbing reasonably large impact forces from berthing ships as well as severe weather conditions, and that is sufficiently rigid so as to provide a consistent transport access between the shore and the ship or ferry. There have been several attempts to design such berthing structures or to design structural elements that can be used on a berth to achieve the energy absorbing goals.
U.S. Pat. No. 5,501,625 (Belinsky, 26 Mar. 1996) discloses a floating terminal for the offshore berthing of very large ships to facilitate transferring cargo between two ships. The floating terminal has a single point anchoring arrangement, consisting of a rigid arm connected to the ship bow and a swivel joint anchored to the sea bottom. A fendering system comprising at least two parallel gravity-type breasting dolphins are permanently attached to at least one of the port and starboard sides of the floating terminal. The specific dolphins employed in U.S. Pat. No. 5,501,625 are disclosed in U.S. Pat. No. 4,331,097 (Belinsky, 25 May 1982). U.S. Pat. No. 4,331,097 discloses a floating breasting dolphin having a pontoon for a ship's berth which absorbs the ship's impact energy by being pivoted and lifted from the surface of the water. A combination of mechanical devices for lifting the main part of the breasting dolphin relatively high off the water is provided. The pontoon of the dolphin is provided with a floodable compartment. Further floating terminal suffers from the disadvantage that an extended area is required to accommodate the movement of the large gravity type breasting dolphins as a ship berths at the floating terminal. Further, this design for a floating terminals suffers from the disadvantage that many moving parts are employed in the dolphin design.
U.S. Pat. No. 5,823,715 (Murdoch, 20 Apr. 1998) discloses a pier structure comprising a floating platform connected to a fixed point shoreline by a fixed position elevated roadway, said pier structure being capable of being rapidly deployed. The mooring system for the floating pierhead structure consists of: a single point mooring anchor system located at the bow of the structure; and four anchor legs located at the stern of the structure. The approachway to the floating pierhead structure is a fixed position, elevated roadway connecting the floating pierhead to the shoreline. The approachway is fabricated from individual spans supported by steel piles which are driven into the ocean floor. A bridge span is provided to connect the floating pierhead structure to the elevated roadway. This floating pierhead structure suffers from the disadvantages that the shoreline to pierhead connection does not dynamically adjust with tides, and further, the impact of a berthing ship must be absorbed by the floating pierhead structure itself.
U.S. Pat. No. 5,107,784 (Lacy, 28 Apr. 1992) discloses a docking system having a plurality of docking members connected end to end. Each docking member is anchored to the seabed. The docking members are lashed together end to end by cables or straps arranged in an X pattern. The space between the docking members is approximately six feet. A walkway of boards or metal extends the entire distance encompassed by the plurality of docking members, connected in a flexible manner to the top surface of the docking members. This docking system suffers from the disadvantage that while convenient for foot passenger travel along the dock, the docking system likely would not support heavier service vehicles or the like nor would it support the movement of vehicles onto the boats. Further, this docking system does not provide the required rigidity and stability for a ferry berth in that a boat impacting on the side of a docking member results in the movement of the docking member. If the applied force is too great, the anchor for that docking member will drag along the seabed and will need to be re-positioned.
U.S. Patent Application No. 2005/0277344 (Haun, filed 9 Jun. 2005) discloses a floating berth comprising a plurality of buoy components that are arranged in a linear fashion and protected by a fendering assembly which constitutes the breasting dolphins of a conventional fixed berth. The buoy components are generally suitable for water depth applications from approximately 100 feet to approximately 10,000 feet.
U.S. Pat. No. 6,470,820 (Wilkins, 28 Oct. 2002) discloses an interlocking connection system that connects modules via interconnecting fingers, male and female, and connector bodies in various states of relative motion between floating structures. The system consists of an arrangement of steel shafts, cams, and connector bodies which, together as male/female elements, can be used to manually lock and unlock floating modules or sections, such as pontoons. The system suffers from the disadvantage in that a number of moving parts must be constructed and aligned in the modules thus adding to the expense.
U.S. Pat. No. 3,695,046 (Torr, 3 Oct. 1972) discloses a fender arrangement for a jetty, said jetty comprising a generally rigid structure mounted to the seabed. Energy absorption by the fender is accomplished with elastomeric tension springs. These fenders suffer from the disadvantage that it is not possible to control the rebound forces of a ship off of the fender.
U.S. Pat. No. 4,697,538 (Day, 6 Oct. 1987) discloses a mooring arm structure having a first arm pivotally mounted to a dock and a second arm attached to the free end of the first arm. An airplane-type shock absorber is connected between the lower end of the second arm and a longitudinal mid-portion of the first arm. This mooring arm structure suffers from the disadvantage for present purposes that a mating mount for the free end of the second arm must be mounted on the docked vessel. The mooring arm structure of U.S. Pat. No. 4,697,538 is specifically adapted to moor fore and aft portions of a water vessel to an associated dock and is not adapted to accommodate the potentially large impact forces presented by an incoming ship or ferry.
U.S. Pat. No. 4,137,861 (Brummenaes, 6 Feb. 1979) discloses a method of mooring a very large ship at a ship's terminal, said method incorporating a fender having a hydraulic damping means and a cooperating pressure relieving and recoil preventing means. The method of U.S. Pat. No. 4,137,861, being adapted for the mooring of very large ships, is relatively complicated and expensive in that it incorporates a plurality of mooring winches for hauling the ship towards the terminal, and pressure monitoring means for monitoring the force of a ship against a fender, and a means for discharging the pressure when the pressure in the hydraulic damping means exceeds a predetermined limit.
U.S. Pat. No. 4,441,449 (Biaggi, 10 Apr. 1984) discloses a port ramp for access to a ship, having a first end supported by a quay and a second end supported by a float, the float being anchored by blocks to the seabed. The float is partially ballastable, that is, its buoyancy may be caused to vary by adjusting the ratio of water to air in the compartments of the float. In order to match the height of the ramp to the appropriate ship deck, the lie of the float supporting the ramp in the water must be adjusted by ballasting the float.
International Patent Application No. PCT/SE89/00297 (Ivarsson, filed 25 May 1999; International Publication No. WO 89/11564, published 30 Nov. 1989) discloses a ramp for a ferry berth, one end of said ramp being elastically connected to the quay and the other end, which is vertically adjustable relative to the water surface, is supported by a floating member. The floating member may be trimmed with a suitable ballast for level adjustment of the ramp. Hydraulic actuators are provided on the quay side end of the ramp for raising and lowering the ship end of the ramp. This ramp suffers from the disadvantage that significant strain is placed on the hydraulic actuators since the actuators must adjust a mass having a long lever arm. Further, the floating member is submerged at a depth intended to be sufficient to eliminate or at least reduce the effects of surface wave action. Accordingly, the floating member cannot serve as a means for service vehicles to access the sides of a vessel in the berth.
European Patent Application No. 87850148.5 (Oleborg, filed 30 Apr. 1987; Publication No. 0 245 227 A2, published 11 Nov. 1987) discloses a ramp spanning the distance between a quay and a pontoon float, the ramp being vertically pivotally connected to the quay. Hydraulic damping means are connected to the distal end of the ramp, the hydraulic damping means being designed to slow down the speed of pivot angle variations between the ramp and the pontoon float. This ramp suffers from the disadvantage that a connection between the shore and a berthed ship that automatically and passively adjusts to changes in water level is not provided.
International Patent Application No. PCT/SE88/00151 (Ivarsson, filed 28 Mar. 1988; International Publication No. WO 88/07605, published 6 Oct. 1988) discloses a loading ramp for a ferry, the loading ramp having two articulately interconnected sections, an inner section elastically connected to a quay, and an outer section, supported by floating members, the outer section supported above a horizontal ramp section. When a ferry lands at the loading ramp, the horizontal ramp section is lowered towards the ferry with hydraulic actuators. The ferry is provided with an end shelf designed to accept the horizontal section. The loading ramp suffers from the disadvantages that the ferry must be specially designed to accept the loading ramp and that only a single access ramp is provided.
U.S. Pat. No. 6,073,571 (Whitener, 13 Jun. 2000) discloses a mooring and ramp system for ferries. The ramp subsystem is carried on a float which is connected to the shore by a ramp hinged to the shore and to the float. A second ramp is hinged on the float and is adjustable to serve each deck of a multi-deck vessel in sequence. The mooring subsystem connects an end of the vessel to the float and allows lateral translation of the vessel relative to the float. A disadvantage of the mooring and ramp system is that the vessel must have a mating piece installed on the vessel to mate with the mooring system.
While various prior berth designs have some degree of isolated merit, none fully meets all objectives of a satisfactory berth for ferries and ships. An ideal improved berth would have a minimum number of moving parts, would provide a berthing platform that is strong and capable of absorbing severe weather conditions and reasonably large impact forces from berthing ships, would passively and automatically accommodate changes in water level, would minimize construction and repair times and costs, and would minimize environmental impact consistent with meeting the other objectives.